[llvm-commits] CVS: reopt/lib/LightWtProfiling/TraceToFunction.cpp

[Brian Gaeke]

Changes in directory reopt/lib/LightWtProfiling:

TraceToFunction.cpp updated: 1.34 -> 1.35

---
Log message:

Since FLI blocks are only inserted on back-edges, make
isFirstLevelInstrumentationBlock() return the back-edge target.
This should allow us to fold the branch into the block's predecessor. 

Make fixupFunctionBodyBB() call it to try to detect FLI blocks.


---
Diffs of the changes:  (+17 -11)

Index: reopt/lib/LightWtProfiling/TraceToFunction.cpp
diff -u reopt/lib/LightWtProfiling/TraceToFunction.cpp:1.34 reopt/lib/LightWtProfiling/TraceToFunction.cpp:1.35
--- reopt/lib/LightWtProfiling/TraceToFunction.cpp:1.34	Sat May 15 19:28:41 2004
+++ reopt/lib/LightWtProfiling/TraceToFunction.cpp	Sat May 15 19:52:05 2004
@@ -410,22 +410,22 @@
     fixupPhisAndCalls (FI, O2CMap);
 }
 
-/// isFirstLevelInstrumentationBlock - returns true iff BB is a basic block
-/// containing only a call to the first-level instrumentation function.
-/// Basic blocks of this form are inserted by the -instloops pass on loop
-/// back-edges.
+/// isFirstLevelInstrumentationBlock - returns a nonzero value iff BB is a
+/// basic block containing only a call to the first-level instrumentation
+/// function.  Basic blocks of this form are inserted by the -instloops pass on
+/// loop back-edges. The return value is the target of the back-edge.
 ///
-static bool isFirstLevelInstrumentationBlock (BasicBlock *BB) {
+static BasicBlock *isFirstLevelInstrumentationBlock (BasicBlock *BB) {
   BasicBlock::iterator i = BB->begin ();
   // starts with llvm_first_trigger call
   if (!isFirstTriggerCall (*i))
     return false;
-  // next thing is an unconditional branch
-  ++i;
-  if (!(isa<BranchInst> (i) && cast<BranchInst> (i)->isUnconditional ()))
-    return false;
-  // looks like the real thing to me...
-  return true;
+  // Next instr. should be an unconditional branch - return its target, or NULL if
+  // there is a mismatch.
+  BranchInst *BI = dyn_cast<BranchInst> (++i);
+  if (!(BI && BI->isUnconditional()))
+    return 0;
+  return BI->getSuccessor (0);
 }
 
 /// fixupFunctionBodyBB - Given srcB in T and its clone dstB in F, and
@@ -480,6 +480,12 @@
 	   && "Trace-exiting branch's clone is null, or not a branch?");
     BranchInst *BIinF = cast<BranchInst> (V);
     for (unsigned i = 0; i < BI->getNumSuccessors (); ++i) {
+      if (BasicBlock *backEdgeTarget =
+          isFirstLevelInstrumentationBlock (BI->getSuccessor (i))) {
+        std::cerr << "Branch instr " << *BI << " looks like an instrumented "
+                  << "backedge from " << srcB->getName() << " to "
+                  << backEdgeTarget->getName () << "\n";
+      }
       if (!T.contains (BI->getSuccessor (i))) {
 	// This is a trace-exiting destination of branch BI. Create a new
 	// basic block FB for its destination in the function.